26, Under active thyroid causing period problems & looking to get pregnant

Hi, I had half of my thyroid removed when I was 14 but was not prescribed thyroxine. I was advised to have it checked yearly which I did. I am 26 and came off the pill almost a year ago. Since then I haven't had regular periods. I went to the doctors 5 weeks ago, had a blood test and was told my thyroid was slightly under active and was prescribed 50mg of levothyroxine. After one week of this I began what I would call spotting, normally would come a couple of times a day and has done for about 4 weeks now. Every odd day I get cramps etc. I haven't actually spoken with my doctors since my test result came back, the nurse just explained my results over the phone. I'm just looking for some advice on what is going on with my body. Me and my partner are looking to get pregnant however nothing happened before my test results and now I'm reluctant to try until my levels sort out. Please can someone help? Thank you.

10 Replies

Welcome to the forum, MH66.

Low thyroid hormone can temporarily stop menstruation and make conception difficult. Do you know what your TSH level was at diagnosis? TSH >3.0 can make it difficult to conceive. The recommended level for women planning conception is 0.4 - 2.5 so make sure your GP knows you are planning a pregnancy so s/he can ensure you are optimally dosed. Dose is usually increased by 25-50mcg when pregnancy is confirmed to ensure good foetal developement and to avoid post partum psychosis.



The goal of Levothyroxine is to restore the patient to euthyroid status. For most patients that will be when TSH is 1.0 or lower with FT4 in the upper range. FT4 needs to be in the upper range in order that sufficient T3 is converted. Read Treatment Options in thyroiduk.org.uk/tuk/about_...

For maximum absorption Levothyroxine should be taken with water 1 hour before, or 2 hours after, food and drink, 2 hours away from other medication and supplements, and 4 hours away from calcium, iron, vitamin D supplements, magnesium and oestrogen.

It takes 7-10 days for Levothyroxine to be absorbed before it starts working and it will take up to six weeks to feel the full impact of the dose. Symptoms may lag behind good biochemistry by several months.

You should have a follow up thyroid test 6-8 weeks after starting Levothyroxine. Arrange an early morning and fasting (water only) blood draw when TSH is highest, and take Levothyroxine after your blood draw.


Thank you for this. I normally take my medication at 6am and have breakfast at 7.30am. I normally have low fibre cereal with milk. Is this a suitable breakfast to have as I've heard things about not having calcium for 4 hours afterwards? Thank you


That's fine. It's calcium supplements which should not be taken within 4 hours of Levothyroxine.


Welcome to our forum,

Long term low thyroid hormone is also an instigator of infertility.

The body will act to stabilize the thyroid hormone imbalance by releasing additional TRH (thyroid-releasing hormone) to stimulate the release of TSH (thyroid-stimulating hormone). Encouraging further TRH will also increase prolactin production which negatively impacts ovulation.

Also, your bodies own response to long term low thyroid hormone is to rely on cortisol (adrenal hormone). Prolonged cortisol elevations will decrease the liver’s ability to clear excess estrogens from the blood, which then increase the levels of thyroid TBG (transport proteins that thyroid hormone is attached to). When thyroid hormone is bound to TBG, it is inactive as must be cleaved from TBG to become “free-fraction” and activate cellular receptors, so making the problem worse... (shown in lab tests as “free T4 [FT4]” and “free T3 [FT3]”.

Levothyroxine takes up to 6 weeks to initially saturate the body which will only tolerate small increases at any one time. The goal of Levothyroxine is to restore the patient to euthyroid status and for most people that means TSH just above or below 1.0 but your doctor should retest your thyroid hormone levels after 6 weeks and adjust the dose according to results, knowing you are hoping to conceive.

Leave 24 hours between last dose and blood draw and have the blood drawn early in the morning whilst fasting (water only) as this is when TSH is highest.

It is important to take your pill on an empty stomach with a glass of water, 1 hour before food, 2 hours before supplements and 4 hours before calcium, iron or vit D supplements. People with thyroid issues often have vitamin deficiencies so ask your doctor to test Vit B12, vit D, folate and ferritin as optimum levels are required to ensure thyroid meds are used properly.

If you post any future blood test results complete with ranges ( numbers in brackets) members will comment. Symptoms can often last many months, even after good biochemistry results.

NICE advise to delay conception until stabilised on levothyroxine (LT4) treatment. If your doctor is awkward, ask for an endo referral.

Good luck ...





Adrenal & Thyroid Connection



Sex Hormones



Infertility and Miscarriage in Subclinical Hypothyroidism.





Thank you for this. I normally take my medication at 6am and have breakfast at 7.30am. I normally have low fibre cereal with milk. Is this a suitable breakfast to have as I've heard things about not having calcium for 4 hours afterwards? Thank you. Getting tested next week again so I will ask for details of my results so I can't post them on here.

Hi MH66. I just want to encourage you with my story. After the birth of my second baby (and the initial bleeding you get for weeks after birth) I didn't have any more periods for almost a year. We wanted a third baby, so went to the doctor. Over a few weeks I saw two doctors - both male - both of whom said this was not unusual after giving birth (even though it didn't happen with my first baby), and dismissed all my other symptoms (feeling tired, depressed, etc.) as being due to having had a baby. Eventually I saw a woman doctor - straight away she checked my pulse - which was very low at 54 - and did a blood test. The next night she phoned me and told me the blood results showed I had myxoedema (very underactive thyroid) and started me on a low dose of thyroxine. Three months later I had a period - and got pregnant! It was regarded as a high risk pregnancy but I had no problems, and the month my son was two I had my daughter. I think my thyroid had been 'dying' for a long time as I always had very irregular periods, and my sons had weighed 5lb 15oz at birth (18 days early) and 5lb 10oz (3 days late) - my daughter weighed in at 9lb 2oz!

Thank you, I really appreciate this. It's just frustrating as previous to all this I used to have very heavy periods and now it's so strange to go from that, to practically nothing for 3 months apart from spotting. I'm just hoping it sorts itself soon. I suppose I have only been on the meds for 5 weeks now. I am getting bloods taken on Monday again and I will be sure to ask for details of my results. X

Hi plz get your levels sorted as meds will need to be upped. Once pregnant speak to a doc who specialise in pregnancy and thyroid issues

Thank you. I have heard that if I'm lucky enough to get pregnant the dose would have to be increased. Hopefully everything will regulate soon.

Good luck I never had issues conceiving it was miscarriage had a few and late pregnancy miscarriage plz speak to your doc asap

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